The invention relates to a drive device for the viewfinder mirror of a single-lens reflex camera, where the mirror carrier and viewfinder mirror assembly is mounted on a pivot shaft in the manner of a crankshaft.
Such drive devices possess the advantage that a relatively small pivoting space is necessary for the viewfinder mirror between picture-taking position and viewfinding position. In one known drive device the viewfinder mirror is mounted on the pivot shaft at its upper edge close to the apex of its pivoting angle and a spring seeks to draw the viewfinder mirror against an abutment flange extending parallel with the pivot shaft and connected rigidly with the pivot shaft, in order to avoid undesired rotation of the viewfinder mirror about the crank axis (GFR P.S. No. 2,626,150). This hinge-type connection of the viewfinder mirror with the crank spindle requires relatively stable formation of the abutment flange and a correspondingly powerful abutment spring, so that the total mirror mass to be accelerated is increased.